Three cadres of the outfit were planting the IEDs when the incident took place at around 3 AM, a spokesman at the state police headquarters said here.
"The cadres had already planted two IEDs and when they tried to plant the third one, it went off," Kanubari MLA Ganriel D Wangsu informed when contacted.
The site of the blast was located at Longding-Wakka road, the sources said adding, the road is in hilly terrain.
SP Dheeraj Kumar could not be contacted.
This is the second incident after a group of 35 NSCN (K) rebels fired upon an Assam Rifles camp at remote Lazu in Tirap district on June 7 last.
No casualty was reported in that shootout.